Mail Relay Disabled on Exchange Server

Third party mail relaying occurs when a UC messaging system allows an external (to UC) user's e-mail client to send mail through UC to a non-UC e-mail address. This is a misuse of the university's funded resources and can interfere with the legitimate work of UC students and employees. Mail relaying is often used to send spam.

Spam is unsolicited mail sent to a number of e-mail addresses, usually to solicit business. It is not only annoying or offensive but can also be harmful to the e-mail system by flooding the mail queue of the mail server or of an individual user. By using a mail relay, a spammer tries to hide the true source of the spam. By spoofing (using a false or fake e-mail address), the spammer hides the true e-mail address from which the spam was sent.

A greater problem is mail relaying which results in university e-mail users being unable to communicate with certain Internet users. Mail servers at some organizations will not accept mail from any messaging systems which allow mail relaying. Lists such as the Open Relay Blocking System (ORBS) list and the Mail Abuse Protection System (MAPS) Real-time Black hole List (RBL) identify servers which allow relaying.

Third party mail relaying most often occurs when a PC user tries to send mail to a messaging system to be delivered to a recipient that is not on the same messaging system . The user configures his or her e-mail address in the mail software (such as Eudora, Netscape, or Pegasus). The user enters his or her own e-mail address (i.e., the address of the server where the user has the account) and also chooses a mail server from which the PC will obtain outgoing mail (SMTP) service. The user should obtain outgoing mail (SMTP) service from the mail server on which he or she has an account. If the user selects some other mail server, third party mail relaying will take place.

The Exchange messaging system will only allow third party mail relaying if the message originates from a computer physically connected to the UC network. UC PPP service is physically connected to the UC network. In other words, third party mail relaying may only be allowed from an IP address that is on the UC network (i.e. 129.137.n.n - .UC.EDU).

What if you are using a different Internet Service Provider (ISP) to access the Internet from home? Those who have a Internet Service Provider (ISP) should use the ISP's mail server to send their outgoing mail. Attempts to use Exchange from an external ISP will result in an error message and nondelivery of the outgoing mail. This situation applies only to those who are using a POP client (Eudora, Netscape, Pegasus, etc.) to access their Exchange accounts and have configured the client to use UCMAIL.UC.EDU to obtain outgoing mail (SMTP) service for mail they send to others at UC or on the Internet.